NAME

snap — FreeBSD UFS2 Snapshot Management Tool

SYNOPSIS

DESCRIPTION

You can use the snap utility to periodically create new snapshots while rotating the olds. It can also be used to manually create snapshots.

The options are as follows:

-p

Perform periodic task. It can only be used on the hour, otherwise nothing will happen. If “atHour” is given in the configuration file, then snap will only run on the specified hour. When this flag is not given, it is considered as a manual snapshot creation.

-m

List manually created snapshots and then exit.

-h

Show the help message.

-c config_file

Specify the pathname of an alternative configuration file; The default is /usr/local/etc/snap.conf.

The snap utility reads its configuration file when it starts up. If filesystems are given and corresponding entries in the configuration file can be found, snap will only handle these filesystems and ignore their “enable” flag in the configuration file.

All snapshot files are created with the local creation time as their filename. In periodic maintaining task, three types of periodic snapshots, namely, hourly, daily, and weekly, are created and rotated according to the settings in the configuration file. They are also hard-linked to “nicknames”, for example, the last hourly snapshot is hard-linked to hour.0.

EXAMPLES

The following command creates snapshots manually according to the configuration file.

To perform periodic maintaining, invoke snap in /etc/crontab as

since periodic maintaining requires to be performed on the hour.

To manually create snapshots on filesystem / and /home and /var only:

This command will ignore the “enable” flag in the configuration file. If, say, /var is not found in the configuration file, nothing would happen.

We can list manual created snapshots on filesystems / and /home:

or also specify an alternative path for the configuration file:

FILES

/usr/local/etc/snap.conf

configuration file

hour.0

last hourly snapshot

daily.0

last daily snapshot

week.0

last weekly snapshot

SEE ALSO

mount(8), crontab(5), mdconfig(8), snapshot(8)

AUTHORS

This manual page was written by Wu Chin-Hao wchunhao@cs.nctu.edu.tw.